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Alteration of N nutrition in Myrica gale induces changes in nodule growth, nodule activity and amino acid composition
Author(s) -
Baker Andrea,
Hill Graham F.,
Parsons Richard
Publication year - 1997
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1997.tb05366.x
Subject(s) - nodule (geology) , myrica rubra , composition (language) , biology , botany , food science , art , paleontology , literature
Changes in nodule growth and activity and in the concentrations of soluble N compounds in nodules, leaves and xylem sap under conditions of altered N nutrition in the actinorhizal plant Myrica gale L. are reported. Altering the N nutrition of symbiotic plants may alter the internal regulation of combined N which in turn may regulate nodule growth and activity. Flushing nodules daily with 100% O 2 caused a decline in amide concentration and an increase in nodule growth although plants had recovered some nitrogenase activity within 4 h of exposure to O 2 . Samples of nodules, leaves and xylem sap were derivatized and amino acids identified and quantified using either reverse phase high performance liquid chromatography or gas chromatography‐mass spectrometry in single ion monitoring mode. The ratio of asparagine in the nodules to that in the xylem was much higher in plants fed N (6.7 for NH + 4 ‐fed and 8.3 for NO − 3 ‐fed plants) than for N 2 ‐fixing plants (2.5). Significant amounts of 15 N added as 15 NH + 4 or 15 NO − 3 accumulated in nodules following accumulation in the shoot which is consistent with the translocation of N to the nodules via the phloem. The uptake of 15 NH + 4 led to the synthesis and subsequent translocation of glutamine in the xylem sap. These results are discussed in terms of the feedback mechanisms that may regulate nitrogen fixation in Myrica root nodules.